I wonder why people always try Google maps first...
Because it's built into so many android phones, and its free, and people are used to it on their computers. That would be my guess.
Don't disagree that there are other apps for navigation, I've tried some of them. Found them to be of as limited worth as Google Maps. I have not tried the Tomtom app, but since the app costs almost as much as a new Tomtom on sale, not going to be trying it.
Maybe I'll feel differently with the Harley out of long pavement trips, but when I'm crashing around on dirt roads or trails and the like, I can barely see anything anyhow, let alone a little GPS screen. And, I rather like having a waterproof(ish) unit with mechanical buttons, not a touch screen that ignores my gloves or cold fingers.